Cameras are incorporated in a wide array of devices. Consumer electronics devices such as mobile phones, tablets, and laptops generally include a compact camera module. The majority of such devices are equipped with a lens system composed of plastic lenses in a fixed configuration. To comply with the steadily decreasing form factor of such devices, the imaging objective of the camera module must have a low profile. For example, a modern camera phone may have a thickness of less than 10 millimeters (mm), including the casing itself. While complying with these challenging form factor requirements, the camera module must provide high-resolution images. This imposes constraints on both the lens system and the image sensor. Typical camera modules have pixel resolution around two megapixels or higher. With such a large number of pixels sharing incident light, the associated lens system must have high light collection efficiency in order to generate a sufficiently bright image. To avoid vignetting, the lens system must generate an image circle that is at least as large as the image sensor. Most image sensors, with pixel resolution of 2 megapixels or higher, have side length of a few millimeters. Thus, an associated lens system must generate an image circle with a diameter that is at least a few millimeters.